1. Field of the Invention
This invention relates to a novel phthalocyanine compound, a method for the production thereof, and a near infrared absorbing dye, heat ray shielding material, and near infrared absorbing material formed by using the compound.
2. Description of the Related Art
In recent years, a plasma display panel (hereinafter abbreviated as “PDP”) which can be applied to a large image plane on a thin wall has been attracting attention. The PDP, however, entails the problem of emitting near infrared radiation during the course of plasma discharge and suffering the near infrared radiation to induce malfunctioning of such electrical apparatuses as domestic TV sets, room coolers, and video decks.
For the purpose of solving the problem of this sort, phthalocyanine compounds having a specific structure have been disclosed in the official gazette of U.S. Pat. No. 6,323,340. These phthalocyanine compounds are characterized by manifesting high permeability to visible radiation and high efficiency of cutting near infrared radiation, possessing excellent ability to permit selective absorption in the near infrared region, and excelling in resistance to heat, light resistance, and weatherability.
There is also an invention which concerns a near infrared radiation-shielding film possessing prominent ability to shield off near infrared radiation and ability to transmit visible radiation (the official gazette of JP-A-2001-133624). This near infrared radiation-shielding film is formed by laminating a transparent resin film layer, a transparent near infrared radiation-shielding layer containing an agent for absorbing near infrared radiation, a transparent resin film layer, and a transparent color tone smoothing layer containing a coloring material capable of smoothing the color tone of the shielding layer and it uses a diimonium type compound as the agent for absorbing near infrared radiation.
In order for the film to be effectively used in a panel such as for a display, it calls for color tone as a quality as well as the property for absorbing near infrared radiation and requires the color tone thereof to be adjusted generally by mixing several kinds of dyes. Some of the dyes which possess an absorbing property in the near infrared region suffer their properties to vary when they are admixed with other dyes or suffer their abilities to absorb near infrared radiation to be varied by a chemical reaction or an inductive interaction. Further, since the manufacture of a panel involves a step for carrying out a melt extrusion or a reaction of polymerization at elevated temperatures, it requires to use a thermally and chemically stable near infrared absorbing material. With a view to coping with a problem such as this, the near infrared absorbing filter which is formed by resorting to such methods as, for example, a casting method or a coating method which uses a solution having a dye possessing an ability to absorb near infrared radiation and a macromolecular resin homogeneously mixed in a solvent, a method of melt extruding a blend of such dye and macromolecular resin, and a method of polymerizing or solidifying a homogeneous mixture of a dye possessing an ability to absorb near infrared radiation with a monomer has been disclosed (the official gazette of JP-A-2002-82219). Since some of the dyes suffer their properties to vary when they are admixed with other dyes, yield to chemical reactions or induced interactions, or lack thermal stability, this filter is made to acquire a capacity for absorbing near infrared radiation in a range fit for an intended application by producing component films by forming methods appropriate to their properties and laminating the component films. The agents for absorbing near infrared radiation include polymethine dyes and phthalocyanine compound type dyes, for example.
The near infrared absorbing film having a resin layer measuring 1–50 microns in thickness and containing at least one kind of near infrared absorbing dye having the maximum absorption wavelength in the range of 800–1200 nm (A dye) and at least one kind of B dye having the maximum absorption wavelength in the range of 575–595 nm and a half-value width of not more than 40 nm formed on a transparent substrate has been also disclosed (the official gazette of WO 02/052531). Phthalocyanine compound type dyes are cited as examples of the near infrared absorbing dyes possessed of the maximum absorption wavelength in the range of 800–1200 nm. Cyanine type dyes are cited as examples of the B dyes possessed of the maximum absorption wavelength in the range of 575–595 nm and a half-value width of not more than 40 nm.
The near infrared absorbing material which uses a transparent resin coating film containing a near infrared absorbing dye and a dye capable of selectively absorbing a wavelength in the range of 550–620 nm has been also disclosed (the official gazette of JP-A-2002-200711). This wavelength corresponds to the orange light that obscures an image and the selective absorption aims to remove this wavelength. In the official gazette, dithiol nickel complexes and diimonium compounds are cited as examples of the near infrared absorbing dye and cyanine type dyes are cited as examples of the dye for selectively absorbing the orange light (in the range of 550–620 nm) respectively. Further, for the near infrared radiation-shielding filter for the use in display, the good transmission in the visible light range is as important a factor as the interception of the near infrared radiation.
It is an object of this invention to provide a phthalocyanine compound capable of forming such a filter as, for example, a near infrared absorbing filter which represses malfunction of remote control by absorbing near infrared radiation of a longer wavelength which causes the difficult absorption by the conventional phthalocyanine compounds and possesses a high transmittance to visible light enough to obtain a clear image as well.
It is another object of this invention to provide a pthalocyanine compound excelling in solubility in a solvent, in compatibility with resin, and in heat resistance, light resistance, and weatherability and a method for the production thereof.
It is yet another object of this invention to provide a near infrared absorbing dye using the phthalocyanine compound and a heat ray shielding material, near infrared absorbing filter, and near infrared absorbing material containing the dye.